I know that Adobe probably plans to "eliminate" another useful piece of software but I figured I'd try and find some answers anyhow. So I've updated to the latest and greatest 4.6 but I can't for the life of me get Squiggly to work with the latest Spark components (TextInput or TextArea).

For Spark components you need to use SpellUIForTLF class. With this class spellcheck works fine, unfortunately TextContainerManager:getContentBounds throws the null pointer exception and I don't know why this happens.

What wasn't obvious to me was that support for these components is in the libs/AdobeSpellingUIEx.swc file (rather than libs/AdobeSpellingUI.swc), which seems to provide an alternative/extended version of SpellUI.enableSpelling(...).

The trick was to remove the libs/AdobeSpellingUI.swc file, which ensures that the correct version of SpellUI.enableSpelling(...) is used. I stumbled on this in abother post: http://forums.adobe.com/thread/870995

The example from intelligent is exactly correct, except that the screen shot of the libs folder shows that the AdobeSpellingUI.swc file has not been removed. If this file is removed, the example should work as desired, with Spell Checking on both Spark and MX components.

To summarise, to support Spark components (as well as MX components):

Use SpellUI.enableSpelling(...) as documented, not SpellUIForTLF.enableSpelling(...).

Make sure you are using libs/AdobeSpellingUIEx.swc (by removing libs/AdobeSpellingUI.swc).